loop8: detected capacity change from 0 to 64
hfs: unable to locate alternate MDB
hfs: continuing without an alternate MDB
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.8.816/11265 is trying to acquire lock:
ffff888052dda0b0 (&tree->tree_lock#2/1){+.+.}-{3:3}, at: hfs_find_init+0x17e/0x1f0 fs/hfs/bfind.c:-1

but task is already holding lock:
ffff888052dda0b0 (&tree->tree_lock#2/1){+.+.}-{3:3}, at: hfs_find_init+0x17e/0x1f0 fs/hfs/bfind.c:-1

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&tree->tree_lock
#2
/1);
  lock(&tree->tree_lock#2/1);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.8.816/11265:
 #0: ffff888066362418 (sb_writers#30){.+.+}-{0:0}, at: vfs_write+0x20e/0x940 fs/read_write.c:580
 #1: ffff88805ce5a9b8 (&sb->s_type->i_mutex_key#33){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff88805ce5a9b8 (&sb->s_type->i_mutex_key#33){++++}-{3:3}, at: generic_file_write_iter+0x83/0x2e0 mm/filemap.c:4149
 #2: ffff88805ce5a7f8 (&HFS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xdb/0x1220 fs/hfs/extent.c:397
 #3: ffff888052dda0b0 (&tree->tree_lock#2/1){+.+.}-{3:3}, at: hfs_find_init+0x17e/0x1f0 fs/hfs/bfind.c:-1
 #4: ffff88805ce5e8f8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xdb/0x1220 fs/hfs/extent.c:397

stack backtrace:
CPU: 1 PID: 11265 Comm: syz.8.816 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x5d40/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 hfs_find_init+0x17e/0x1f0 fs/hfs/bfind.c:-1
 hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
 hfs_extend_file+0x2ef/0x1220 fs/hfs/extent.c:401
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x317/0x1220 fs/hfs/extent.c:401
 hfs_get_block+0x3d8/0xbd0 fs/hfs/extent.c:353
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 __block_write_begin fs/buffer.c:2173 [inline]
 block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
 cont_write_begin+0x5c8/0x7e0 fs/buffer.c:2591
 hfs_write_begin+0x8b/0xd0 fs/hfs/inode.c:58
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x43b/0x940 fs/read_write.c:584
 ksys_pwrite64 fs/read_write.c:699 [inline]
 __do_sys_pwrite64 fs/read_write.c:709 [inline]
 __se_sys_pwrite64 fs/read_write.c:706 [inline]
 __x64_sys_pwrite64+0x195/0x220 fs/read_write.c:706
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3b1378f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3b1455a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f3b139e5fa0 RCX: 00007f3b1378f749
RDX: 00000000fffffe71 RSI: 0000200000000080 RDI: 0000000000000005
RBP: 00007f3b13813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7c R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3b139e6038 R14: 00007f3b139e5fa0 R15: 00007ffe9e5493a8
 </TASK>